In connection with radio frequency chips, there is a need to decouple radio frequency AC components from DC control and supply currents as close to the chip as possible.
To meet that need, a number of separate capacitors of different capacitance values are used. A small capacitor may e.g. be placed on the chip to decouple AC components of the highest frequencies, while a somewhat larger capacitor may be placed on the chip module close to the chip to decouple AC components of lower frequencies, and at least one further, larger capacitor may be placed on the circuit board close to the chip module to decouple AC components of the lowest frequencies.
To use a plurality of capacitors is quite expensive. Moreover, a decoupling capacitor on the chip itself requires a lot of space on the chip.